JP3031196B2 - Color picture detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture detecting apparatus for irradiating a color picture with light and measuring geometric data such as the size, position and shape of the picture by reflected light.

[0002]

2. Description of the Related Art Light is radiated on a color print, and the reflected light is detected by a light receiving sensor such as an image sensor or a photodiode to detect the size, position, shape, etc. of the picture. FIG. 8 shows a line follower control device using such detected values, and a slitter machine for cutting at high speed and high accuracy in accordance with a picture or the like printed by the control device. The unwinding reel 1 is wound with a web 10 in which the same pattern printed by the plate cylinder is arranged in two rows. Web 10
A register line 2 is printed on the right end of the mark, and cutting is performed by a slitter machine based on the register line 2. Therefore, the register line 2 is detected, and the swing block 5 including the unwind reel 1 and the guide roll 4 is controlled so that the register line 2 is always sent to a constant reference position. The follower head 6 is set at a position almost directly above the register line 2. The line follower head 6 detects the amount of deviation of the register line 2 from the reference position. The reference position is a target position of the register line 2. When the register line 2 passes through the target position, the web 10 is cut by the cutter blade 3 at an appropriate position corresponding to the pattern. For this reason, the deviation from the reference position is detected and sent to the control unit 7, the drive amount is instructed from the control unit 7 to the actuator 8, and the swinging block 5 is moved by the actuator 8 in the lateral direction to make the deviation zero. I do.

FIG. 9A shows a pattern 11 and a register line 2 printed on a web 10, and FIG. 9B shows a measurement signal of the register line 2 by an image sensor as a line follower head 6. The pattern 11 is printed in multicolor by a plate cylinder for each color, but the register line 2 is printed by one of the plate cylinders in a color to be printed on the plate cylinder. When no line is detected, by stopping the actuator, a part of the pattern 11, for example, the vertical frame 11 a of the pattern 11 can be used without providing the register line 2. Therefore, the register line 2 is also handled as a part of the picture 11. The pattern 11 is usually printed in color on a white background or a transparent background. The line follower head 6 is provided on the guide roll 4 as shown in FIG. 8, and the guide roll 4 is close to a strong white color when viewed from directly above the specular reflection surface by chrome plating or the like. The ground of the pattern 11 and the register line 2 is bright white, and the pattern 11 and the register line 2 are darker than the ground because they are colored. This dark place is captured by an image sensor, and its position, shape, and the like are detected.

FIG. 9B shows the output of a one-dimensional image sensor. In a one-dimensional image sensor, for example, 1024 or 2048 light receiving elements are arranged in a line, and the output of each light receiving element is extracted for each pulse. Therefore, if the first pulse corresponds to the first light receiving element, the output of each light receiving element can be determined by counting the number of pulses, and the position of each light receiving element is determined on the image sensor. The changed position of the light receiving element is known. The length of the light receiving element portion of the image sensor corresponds to the length of the web 10 due to the lens system. If the position of the light receiving element on the image sensor where the output change occurs is known, the output change occurs on the web 10. The position of the register line 2 can be measured. The distance L in (b) indicates the position where the output has dropped below the white background due to the register line 2. TH indicates a threshold value. When the threshold value falls below the threshold value, TH is determined as the register line 2 and distinguished from noise or the like. The distance L is measured by the number of pulses, and is obtained by multiplying the number of pulses by a value obtained by dividing the length of the light receiving element by the total number of light receiving elements. The image sensor is fixed, and the web 10 moves. When the web 10 is shifted in the horizontal direction, the register line 2
Are also shifted, this shift can be detected.

When measuring the positions and dimensions of such pictures, it is not necessary to determine the colors of these pictures, but the pictures 2 and 11 including the register line 2 are displayed in color. , The pattern represented by the color used 2, 11
Need to be detected. In the case of color printing, there are commonly used colors such as black, magenta, yellow, cyan, and others.Incandescent lamps, halogen lamps, or fluorescent lamps that irradiate a wide wavelength light are generally used as light sources for illumination. ing. Recently, a blue light emitting diode having a short wavelength has been put to practical use, so that three colors of red, green, and blue or red,
It is described in Japanese Patent Publication No. 6-98748 public information that two blue colors are simultaneously emitted and used as a light source for illumination.
On the other hand, as the detector, there are a case where a detector of three colors of red, blue and green is used, and a case where a monochrome black and white detector is used.

[0006]

The incandescent lamps, halogen lamps, fluorescent lamps and the like generally used as light sources for irradiating light of a wide wavelength range have a short life and need to be replaced periodically. Further, in the case of such a light source, it is easy to detect a black, red, and blue pattern, but it is difficult to detect a yellow pattern. If this is yellow,
Contains red and green components, absorbs blue light,
The reason for this is that red and green light are reflected, but the red and green reflections are large, and it is difficult to distinguish the white from the highly reflective ground. By irradiating through a blue filter to increase the amount of blue light and absorbing the blue light by the yellow pattern, the yellow red and green components are less in the projected light and less in the reflected light . Therefore, compared with the reflected light on the white background, which reflects almost all the irradiation light, the reflected light on the yellow is reduced, so that the reflected light becomes darker and can be easily distinguished from the white background.

A band cut filter for cutting a wavelength in a yellow region is also used. This is because when illuminated with light of the same color as the printing color, it is almost reflected, and similarly, it is indistinguishable from the white of the ground that is also almost reflected. The yellow pattern is illuminated with light that is rich in red and red components. This reduces the amount of yellow reflected light from the picture, so that even if there is reflected light of another color, the reflected light becomes smaller than the reflected light on a white background, and a yellow picture can be detected.

FIG. 10 is a diagram showing the effect of the filter.
Shows a case where a filter is not used, and (b) shows a case where a yellow region is cut using a band cut filter. The same applies to the case where a blue filter is used. The vertical axis indicates the output (voltage) of the image sensor, and the horizontal axis indicates the position of the picture of each color. The flat line with the maximum value indicates the level of the white background,
The ground of each color indicates a state where the output is lower than that of a white background. Since there is no need to identify the color itself, the image sensor is of a monochrome type. Since black has a large absorption and little reflected light,
The output drops significantly, causing a large difference from a white background. black,
Since the amount of reflected light increases in the order of red and blue, the decrease in output decreases. However, the three colors have sufficiently low outputs, and can be reliably determined by the threshold value TH. In the case of (a) where no filter is used, the output of yellow is reduced little (that is, the reflection of the red component of yellow is large), and exceeds the threshold value TH, making detection difficult. With the filter (b), black and red are not much different, blue is slightly worse, but yellow is greatly improved,
It becomes possible to detect enough.

By the way, the color of the picture is black as described above,
In addition to red, blue, and yellow, pale yellow, pale blue, and pale red or pink are also used. These original colors are closer to white, and since these pale colors have a higher reflectance, they approach the reflectance of the ground white, so the amount of decrease in the output of the image sensor in those colors is reduced. And detection becomes difficult. In particular, in the case of yellow, since the output reduction amount of yellow itself is small, if the output becomes lighter, the output reduction further decreases, so that detection becomes difficult. Note that when a color image sensor is used, the same effect as when a filter is used can be obtained, but it is similarly difficult to detect light colors.

The use of three monochromatic lights of red, green and blue simultaneously as a light source is almost the same as the case of using conventional wide-wavelength light, except that two monochromatic lights of red and blue are simultaneously used. When it is used, the same effect as in the case where the wide wavelength light is cut in the yellow region by the band cut filter has the same effect, and the performance as shown in FIG. 10B is obtained.

The problems of the conventional illumination source described above are summarized as follows. In the case of incandescent lamps, halogen lamps or fluorescent lamps that emit broadband light, their life is short and must be replaced periodically. Further, since it is difficult to detect yellow, a blue filter and a band cut filter are required. Lighter colors,
In particular, it is difficult to detect pale yellow. This is similarly difficult using a color image sensor. When using red, green, and blue monochromatic lights such as light-emitting diodes at the same time, it is the same as the case of broadband light,
Filters are needed to detect yellow, but red,
If blue monochromatic light is used at the same time, no filter is required. Since the life is long, maintenance becomes easy. However, in the case of a light color, it is difficult to detect the light as in the case of the wide wavelength light.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a color pattern detecting device which has a long life, is easy to detect a yellow pattern, and is effective for detecting a pale color. Aim. For this reason, it has been experimentally confirmed that it is easy to detect a pattern of a specific color by irradiating a single color light alone.
It is an object of the present invention to provide a device that receives light with a plurality of light receiving sensors. It is another object of the present invention to make the output of each light source the same so that the peak value of the output of the light receiving sensor becomes a constant value. It is another object of the present invention that a threshold value for judging the output of the light receiving sensor is set to a fixed ratio with respect to the peak value of the output of the light receiving sensor, so that it can cope with the fluctuation of the output. It is another object of the present invention to provide a gate in the field of view of the light receiving sensor so that data in a necessary range can be obtained.

[0013]

According to the first aspect of the present invention, there is provided an illumination source for irradiating a color pattern by alternately switching a red light emitting diode, a green light emitting diode, and a blue light emitting diode; A light receiving sensor for receiving the reflected light from the light source, a timing unit for switching the irradiation of the light sources of the three colors in a cycle corresponding to one scanning time of the light receiving sensor, and an output of the light receiving sensor exceeding a predetermined threshold value A measurement unit that detects the changed position and measures the geometric data of the color pattern.

According to a second aspect of the present invention, an illumination source for illuminating a color picture by alternately switching between a red light emitting diode and a blue light emitting diode, a light receiving sensor for receiving light reflected from the color picture, and one of the light receiving sensors A timing unit for switching the irradiation of the two color light sources in a cycle corresponding to a scanning time, and a measuring unit for detecting a position where the output of the light receiving sensor has changed beyond a predetermined threshold value and measuring the geometric data of the color pattern And

According to a third aspect of the present invention, the illumination source is provided with an automatic brightness adjustment unit that adjusts a peak value of the light receiving sensor for irradiation from each light source to a predetermined value for each irradiation cycle.

According to a fourth aspect of the present invention, a threshold value is determined at a fixed rate with respect to a peak value of a light receiving sensor for irradiation from each light source of the illumination source, and a threshold value is set for each irradiation cycle of each light source. A threshold setting unit is provided for setting the predetermined threshold of the measuring unit.

According to a fifth aspect of the present invention, there is provided a gate setting section for setting a gate which defines a visual field range of the light receiving sensor.

According to the present invention, there is provided an automatic brightness adjusting section for adjusting the peak value of the light receiving sensor in the gate set by the gate setting section to a predetermined value for each irradiation cycle of each light source. It was done.

According to the seventh aspect of the present invention, a threshold value at a fixed ratio with respect to the peak value of the light receiving sensor in the gate set by the gate setting unit is determined, and the threshold value for each irradiation cycle of each light source is determined. A threshold setting unit for setting is provided, and the predetermined threshold of the measuring unit is set.

[0020]

According to the first aspect of the present invention, three monochromatic lights are alternately switched by the red, green and blue light emitting diodes to irradiate a color picture. The light receiving sensor receives each irradiation light at a time corresponding to one scanning time, and outputs the light over one scanning time. The measurement unit detects a position where the output of the light receiving sensor has exceeded a predetermined threshold value and measures geometric data such as a position, a size, and a shape of the color picture. The use of the light emitting diode extends the life of the light source. In addition, only one light-receiving sensor is required to emit light by switching the light source.

In the present invention, the red, green, and blue light emitting diodes irradiate independently, respectively. The function will be described with reference to FIG. 7 shows the output (voltage) of the light receiving sensor on the vertical axis and the color on the horizontal axis, as in FIG. 10, (a) a red light emitting diode, (b) a blue light emitting diode,
(C) shows a green light emitting diode. The maximum value of the output indicates the value of the ground white, and indicates the output of black, red, green, blue, and yellow patterns. Each output is a value obtained by an experiment. TH indicates a threshold value, and if it is below TH, it is assumed to be an output magnitude that can be detected without being influenced by noise or the like. As a common feature of any light emitting diode, the output of black is greatly reduced. Also, the same color as that of the light emitting diode can hardly be detected.
For example, in the case of a red light emitting diode, red cannot be detected.
Red and blue can be detected next to black in the other color light emitting diodes. Green can also be detected next to red and blue. Yellow can hardly be detected in the case of red and green light emitting diodes, but can be detected as well in the case of blue light emitting diodes as red. This is a larger detection value than the case of yellow in FIG. 10 (b), and there is no reflection of the red light component and no absorption attenuation by the filter when irradiating by itself than by using the blue filter. This indicates that the detection sensitivity is good by the amount.

Light yellow, light blue, light red (pink), and the like are those in which the white component of each color is increased. When the color becomes lighter, the output decrease relative to the level of the white background is reduced, and the level approaches the level of the white background. As you move upward, it becomes difficult to determine. For this reason, when the color with the smaller output decrease of the original value becomes lighter,
Detection becomes difficult. In the case of yellow in FIG. 10 (b), the output decreases less than in red and blue, so that pale yellow is difficult to detect.
However, as shown in FIG. 7B, in the case of irradiating only the blue light emitting diode, the output of yellow is greatly reduced, so that even if it becomes faint, the detection ability is higher than the conventional one.

In the case of the green light emitting diode shown in FIG.
It does not appear to be necessary because the black, red and blue detection capabilities are not as good as the other two light emitting diodes. The ability to detect red is also inferior to that of the blue light emitting diode in FIG. However, according to the experimental results, it is superior to the case of the blue light emitting diode of (b) with respect to pale red (pink). Therefore, by alternately illuminating the pattern with red, blue and green light emitting diodes, the color of the pattern is black, red,
Even blue, yellow and their light colors can be detected.

The second aspect of the present invention is different from the first aspect in that two monochromatic lights are alternately switched by red and blue light emitting diodes to irradiate a color picture. The green light emitting diode is excellent in detecting a pink pattern, but other capabilities are lower than the red and blue light emitting diodes. Therefore, if the pink pattern is not used for the register line 2 and the like, the red and blue light emitting diodes are used. Thus, the same effect as that of the first aspect can be obtained.

According to the third aspect of the present invention, even if the web material such as paper or film changes and the reflection efficiency fluctuates, the peak value of the white background portion of the light receiving sensor with respect to the irradiation light from each light source is determined by the automatic brightness adjustment unit. Since the output is controlled to a predetermined value every time, even when the amount of light is large, such as specular reflection, the output of the light receiving sensor does not saturate, stable detection can be performed, and measurement errors are reduced.

According to the fourth aspect of the present invention, the threshold value setting section obtains the peak value of the light receiving sensor with respect to the irradiation light from each light source, and sets this constant ratio as the threshold value, and sets the threshold value for each irradiation cycle. Therefore, the threshold can correspond to the change in the output, and the measurement error is reduced.

According to the fifth aspect of the present invention, since the gate for determining the field of view of the light receiving sensor can be set, only the range necessary for detection can be extracted, the detection can be facilitated, and the error can be reduced. Even if there is an abnormally large reflection portion or an absorption portion outside the detection area, the area can be excluded.

According to the sixth aspect of the present invention, the range of only the target picture is limited by the gate setting unit, and the peak value of the output of the light receiving sensor in the gate is adjusted by the automatic brightness adjustment unit for each irradiation cycle of each light source. Since the predetermined value is set, even if there is a strong reflection portion outside the detection target area, there is no possibility that a peak value including a part outside the detection target is taken, and the measurement accuracy is improved.

According to the seventh aspect of the present invention, the range of only the target picture is limited by the gate setting section, and the threshold value is set by the setting means at a fixed ratio to the peak value of the output of the light receiving sensor in the gate. Is obtained, and the threshold value is obtained for each irradiation cycle of each light source, so that the threshold value for the peak value only in the range necessary for detection can be obtained, and the measurement accuracy is improved.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating an optical system according to the present embodiment. A line image sensor 12 is arranged on an optical axis 14 perpendicular to a web 10 on which a picture is printed, and reflected light and scattered light are imaged on the line image sensor 12 by a lens system 13.
The red light emitting diodes RD and the blue light emitting diodes BD are respectively arranged in a line, and the line image sensor 12 is irradiated with the web 10 as a measurement surface from an oblique direction. This optical system is built in the line follower head 6 described in FIG. 8 and irradiates the web 10 of the guide roll 4. The line image sensor 12 is for monochrome, and the number of light receiving elements used is 1024 or 2048 in a line.

FIG. 2 is a block diagram showing the configuration of this embodiment, and FIG. 3 is a time chart of FIG. In FIG. 2, a timing circuit 20 is a circuit for generating various signals for the constituent blocks, and the whole is controlled by these signals. The timing of each signal is shown in FIG.
Corresponds to A to K in FIG. A is a red light emitting diode lighting signal, and the lighting period is one scanning period of the line image sensor 12. B is a blue light emitting diode lighting signal and A
A and B are alternately lit, although the lighting period is the same. C
Is a sampling signal, and D is a reset signal. E is a narrow gate signal, and F is a wide gate signal. G is a video signal, H is a peak hold signal, I is a red peak level, J is a blue peak level, and K is a threshold.

The image sensor 25 converts a light input into a charge signal, and stores the charge signal in a photoelectric conversion unit, a scanning unit for reading the stored signal charge, and an output unit for outputting the read signal charge as an electric signal. The operation is performed by a pulse from the timing circuit 20. This output is connected to amplifier 2
The video signal G is amplified at 6 and becomes a video signal G. The video signal G shown in FIG. 3 shows the shape of the register line 2 described with reference to FIG. 9B, and the position where the central output is reduced indicates the register line 2, and both sides indicate a white background. The low-pass filter 27 has a smooth curve excluding the high frequency components of the video signal G. The peak hold circuit 28 is a circuit for holding the peak level of the video signal G for each scan, and the gate switch 2
The peak value in the gate signal E or F set by 1 is held, and the hold is released by the reset signal D. The gate signals E and F are used to set the field of view to be detected, and are switched and set by the gate switch 21.

The sample hold circuit 29 is a circuit 29a for holding the peak level I of the video signal G due to red light.
And a circuit 29b for holding the peak level J of the video signal G due to blue light. The image sensor 25 emits light from the light emitting diodes RD,
There is a delay of one scanning time from when the BD is turned on to when the video signal G is output. As shown in FIG. 3, when the red light emitting diode RD is turned on, a blue light signal video signal G is output, and when the blue light emitting diode BD is turned on, a red light signal video signal G is output. . Therefore, the peak level of the video signal G, ie, the output signal H of the peak hold circuit 28, which is shifted by one scanning time after the light emitting diodes RD and BD are turned on, is sampled. The AND gates 22a and 22b are circuits for sampling the video signal G shifted by one scanning time in this manner. The AND gate 22a is a sampling signal C at the time of the signal B and is a peak value H of the video signal G by red light.
Is held by the sample and hold circuit 29a, and the AND gate 22b causes the sample and hold circuit 29b to hold the peak value H of the video signal due to the blue light with the sampling signal C at the time of the signal A.

The automatic brightness adjustment circuit 30 always sets the peak level of the video signal G in the gate signal to a constant voltage (for example, 2
V) a circuit that adjusts the peak level I of the video signal G in the gate signal by red light, and a circuit that adjusts the peak level J of the video signal G in the gate signal by blue light. 30b. The analog switch 23a is closed by the signal A, and the output of the automatic brightness adjustment circuit 30a is amplified by the power amplifier 31a and supplied to the red light emitting diode RD. Similarly, the analog switch 23b is closed by the signal B, and the automatic brightness adjustment circuit 30b
Is amplified by the power amplifier 31b and supplied to the blue light emitting diode BD. Thereby, each light emitting diode R
D and BD output irradiation light so as to always have a constant video signal level (peak level).

The analog switches 24a and 24b, the voltage follower 32, and the potential setting unit 33 signal the peak level I of the video signal G of red light and the peak level J of the video signal G of blue light in synchronization with the scanning of the image sensor 25. A and signal B are switched, and the peak levels I and J of the video signal G based on red light and the video signal G based on blue light, respectively.
, A threshold value K is set at a fixed rate. The analog switch 24a captures the red light peak level I as a signal B, and the analog switch 24b switches the blue light peak level J.
Is taken in by a signal A. The voltage follower 32 keeps the potential constant even when the load fluctuates, and keeps the potential constant even when the resistance change of the potential setting device 33 changes. Potential setting device 3
3 is a threshold K at a certain ratio with respect to the peak levels I and J
Set.

The comparator 34 compares the video signal G with a threshold value K and detects a signal whose output is lower than the threshold value K. The position detector 35 checks the position where the signal whose output is lower than the threshold value K is generated. This position data is used as control data. For example, if the pattern is the register line 2 described with reference to FIG. 8, the control data for operating the actuator 8 and moving the swing block 5 by the control unit 7 so as to make the deviation between the target position and this measurement position zero. .

A video signal G based on a signal A for irradiating the red light emitting diode RD and a video signal G based on a signal B for irradiating the blue light emitting diode BD are alternately input to the comparator 34, and correspond to the respective video signals G. Since the threshold value K is input, each video signal G is compared with the threshold value K. As described with reference to FIG. 7, in the signal A, black, green, and blue patterns show large changes in the video signal G, but in red and yellow, little changes appear. In the signal B, a large change appears in black, red, green, and yellow. The position detector 35 outputs one signal A or B such as red, blue, and yellow.
If the signal can be detected only by using the signal A, the data of that signal is used.

FIG. 3 shows the relationship between the threshold value K and the video signal G.
Will be described. The red light-emitting diode is illuminated by the signal A at this time, and this video signal G is obtained at Video signal G
Is held as the red light peak level I by the sampling signal C.
Becomes the threshold value K at the position where the signal B is taken in by the analog switch 24a at the time of the signal B. At one position, the red light-emitting diode illuminates with the signal A, and a video signal is obtained at the position. The threshold value K for the video signal G is applied. That is, the threshold value K applied to each video signal G is generated by the video signal G one cycle before. This relationship is the same for the blue light emitting diode BD.

FIG. 4 shows a case where the measuring surface 40 perpendicular to the optical axis 14 is inclined as shown by a broken line 41. The optical axis 14 of the line image sensor 12 and the lens system 13 is set perpendicular to the measurement surface 40. When the optical axis 14 is inclined as shown by a broken line 41, the red light and the blue light emitted by the red light emitting diode RD and the blue light emitting diode BD are emitted. , The incident angle to the line image sensor 12 changes, and the light receiving level changes between red light and blue light. Further, when the color of the ground on the measurement surface is not white, for example, in the case of a blue system, when the light is irradiated by the blue light emitting diode BD, the blue is not absorbed by the ground and is reflected, so that the level of the ground is not so different from that of the white ground. On the other hand, when illuminated by the red light emitting diode RD, red is absorbed by the blue of the ground, so that the level of the ground is lower than in the case of white. Since the detection of the picture is based on the difference between the ground level and the light receiving level from the color of the corresponding picture, the detection level decreases as the ground level decreases. Similarly, when the ground is of a red system, the detection level is reduced by irradiating with the blue light emitting diode BD. Therefore, the automatic brightness adjustment circuits 30a and 30b for keeping the emission brightness of each of the red light emitting diode RD and the blue light emitting diode BD at a constant value so that the light receiving level from the ground by the red light and the light receiving level from the ground by the blue light are always constant. And each diode R is set so that the voltage value due to light reception from the ground by the diodes RD and BD becomes, for example, 2V.
Supply power to D and BD.

When the inclination angle of the measurement surface 40 becomes large or the color of the background of the measurement surface becomes dark, the light emitting diodes RD,
Even when the BD emits light up to the rated maximum, the light receiving level from the ground may not reach a predetermined value, for example, 2V. Therefore, the threshold value K is always automatically set at a constant rate with respect to the peak value of the light receiving level from the ground, and the threshold value K for the red light is set to a value earlier than, for example, the red light emitted one cycle before. It is determined from light, and in the case of blue light, it is similarly determined from blue light. This operation is performed by the analog switches 24a and 24b shown in FIG.
Is realized by:

As described with reference to FIG.
In many cases, the line follower head 6 having the built-in 2 is installed on the guide roll 4. The roll is usually chrome-plated or the like, and the amount of reflected light is greater than when the web 10 is paper and has a white background. For this reason, when trying to detect a pattern at the edge of the printed matter, the roll surface may enter the field of view of the image sensor 12 in some cases. In such a case, the light reception level from the roll surface becomes higher than the light reception level from the print surface, and if the threshold value K is set at a fixed ratio with respect to the peak level of the video signal G, the printed pattern is detected. Can not. FIG. 5 shows a video signal including a roll surface. R1 indicates a pattern, in this case, a light receiving level of the register line 2,
R2 indicates the light receiving level of the ground on the printing surface, and R3 indicates the light receiving level from the roll surface. Peak level based on R3
If the threshold value TH is determined at a constant rate with respect to this value, the threshold value exceeds R2.

In order to prevent such a problem, a gate signal synchronized with the scanning of the image sensor is provided, and a threshold value is set at a fixed ratio with respect to the peak level of the video signal G in the gate signal. FIG. 6 is a diagram showing a waveform and a threshold value of a video signal when a gate signal is provided. R1 is the light receiving level of the picture to be inspected, R2 is the light receiving level of the ground, R3 is the light receiving level from the roll surface, and is the gate signal Gt.
Excludes the range of the light receiving level R3 from the roll surface and limits the video signal to a range centered on the light receiving level R1 of the picture. As a result, the peak level Ph becomes the ground level R2.
The threshold value Th is set at a constant rate with respect to this Ph.

The automatic brightness adjustment circuits 30a and 30b for controlling the light emission brightness of each of the light emitting diodes RD and BD also keep the peak level of the video signal in the gate signal at a constant value. In addition, if the detection range is set to capture only the video signal within the gate signal, even if a non-target pattern, etc., is in proximity to the pattern to be detected, erroneous detection may be performed by setting this to the outside of the gate signal. There is no. Several kinds of gate signals are set in advance according to the detection range, and the detection range can be easily set by switching these with a switch. In FIG. 3, two types of gate signals E and F are set, and are switched by a manual gate switch 21.

The setting of the gate signal is to select the output of the light receiving element constituting the image sensor. Since the output of each light receiving element is sequentially output in accordance with the pulse for driving the image sensor, the position and range of the pulse are determined. Specify
By extracting the output of the light receiving element in that range, the output of the light receiving element in an arbitrary position at an arbitrary position can be obtained. A signal indicating the output position and range of the light receiving element is a gate signal.

In the above description, the register line 2 was selected as a picture and the detection of its position was explained.
If a point is detected, its length can be measured, and if three points are detected, its shape can be detected. FIG. 2 shows the case where the light emitting diodes are of two types, red and blue. However, when the light emitting diodes are of three types, red, blue and green, the two systems are replaced with three systems.
This can be easily realized by generating three types of light emission signals in the timing circuit 20. Although the circuit of FIG. 2 is configured so that the color and brightness of the pattern or line to be detected can correspond to various types, the automatic brightness adjustment is not necessarily performed when the range of the target color or brightness is limited to a certain range. Not necessary.
When the detection target area does not include a roll having a large reflection amount or a black background having a large absorption, a gate is not necessarily required.

[0046]

As is apparent from the above description, according to the present invention, a plurality of light emitting diodes are alternately emitted as illumination sources, and a color suitable for each light emitting diode is detected. Can be easily detected. Further, since the detection sensitivity of each color is improved, the detection sensitivity of the pale color is also improved. Further, the detection sensitivity of pink is improved by using a green light emitting diode. Also, since the light sources are turned on alternately, only one light receiving sensor is required, and it is not necessary to provide each light source. Since an automatic brightness adjustment circuit and an automatic threshold setting circuit are provided for each light emitting diode, the inclination of the mounting angle of the device with respect to the measurement surface and the influence of the background color of the measurement surface can be reduced. In this case, it is possible to avoid the influence of the roll surface and the pattern close to the detection target. The use of the light emitting diode extends the life of the light source, greatly reduces the time and labor for replacement, and facilitates maintenance.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an optical system according to an embodiment.

FIG. 2 is a block diagram illustrating a configuration of an embodiment.

FIG. 3 is a timing chart of the embodiment.

FIG. 4 is a diagram illustrating an influence when a measurement surface is inclined.

FIG. 5 is a diagram showing a video signal including a roll surface.

FIG. 6 is a diagram showing a video signal when a gate signal is provided.

FIG. 7 is a diagram showing outputs of light receiving sensors of respective colors when red, blue, and green light emitting diodes are independently irradiated.

FIG. 8 is a diagram showing a line follower control device and a slitter machine controlled by the device.

FIG. 9 is a diagram showing a pattern and a register line printed on a web.

FIG. 10 is a diagram showing an effect of a filter.

[Explanation of symbols]

 2 Register Line 4 Guide Roll 6 Line Follower Head 10 Web 12 Line Image Sensor 13 Lens System 20 Timing Circuit 25 Image Sensor 26 Amplifier 27 Low Pass Filter 28 Peak Hold Circuit 29 Sample Hold Circuit 30 Automatic Brightness Adjustment Circuit 31 Power Amplifier 32 Voltage Follower 33 Potential setting device 34 Comparator 35 Position detector

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 11/00-11/30

Claims (7)

(57) [Claims] An illumination source for illuminating a color picture by alternately switching between a red light emitting diode, a green light emitting diode, and a blue light emitting diode, a light receiving sensor for receiving light reflected from the color picture, and one scan of the light receiving sensor A timing unit for switching the irradiation of the three color light sources at a cycle corresponding to time, a measuring unit for detecting a position where the output of the light receiving sensor has changed beyond a predetermined threshold value and measuring the geometric data of the color pattern; A color pattern detecting device comprising: 2. An illumination source for illuminating a color picture by alternately switching between a red light emitting diode and a blue light emitting diode;
A light receiving sensor for receiving reflected light from the color picture,
A timing unit for switching the irradiation of the light sources of the two colors in a cycle corresponding to one scanning time of the light receiving sensor, and detecting a position where the output of the light receiving sensor exceeds a predetermined threshold value to detect the geometrical data of the color pattern And a measuring unit for measuring the color pattern. 3. The illumination source is provided with an automatic brightness adjustment unit for adjusting a peak value of a light receiving sensor for irradiation from each light source to a predetermined value for each irradiation cycle. Item 3. The color pattern detection device according to Item 1 or 2. 4. A threshold setting for obtaining a threshold value of a fixed ratio with respect to a peak value of a light receiving sensor for irradiation from each light source of the illumination source, and setting a threshold value for each irradiation cycle of each light source. 3. The color pattern detecting device according to claim 1, wherein a unit is provided, and the predetermined threshold value of the measuring unit is set. 5. The color picture detecting device according to claim 1, further comprising a gate setting section for setting a gate for determining a field of view of the light receiving sensor. 6. An automatic brightness adjusting unit for adjusting a peak value of a light receiving sensor in a gate set by the gate setting unit to a predetermined value for each irradiation cycle of each light source. 6. The color picture detecting device according to claim 5, wherein: 7. A threshold value for determining a threshold value of a fixed ratio with respect to a peak value of a light receiving sensor in a gate set by the gate setting unit, and setting a threshold value for each irradiation cycle of each light source. The color pattern detecting device according to claim 5, wherein a setting unit is provided, and the predetermined threshold value of the measuring unit is set.